3D Printing Complex Biological Tissues Via Stereolithography

UCLA Newsroom reports on a recent study exploring how the new 3D printing process of stereolithography can be used to create complex biological tissues.

This study, which was funded by the Office of Naval Research and the National Institutes of Health, was developed by researchers at the UCLA Samuell School of Engineering, Harvard Medical School, the University of Santiago de Compostela, Spain, Sharif University of Technology, Iran, and UC San Diego. The team’s findings were published in the scientific journal Advanced Materials.

The technique involves “a specially adapted stereolithographic 3D printer to build therapeutic biomaterials from multiple materials. The advance could be a step toward on-demand printing of complex artificial tissues for use in transplants and other surgeries.”

As UCLA’s Levi James Knight, Jr., Professor of Engineering Ali Khademhosseini explains, “tissues are wonderfully complex structures, so to engineer artificial versions of them that function properly, we have to recreate their complexity. Our new approach offers a way to build complex biocompatible structures made from different materials.”

Stereolithography is a 3D printing process involving light. Khademhosseini’s custom-built 3D printer “has two key components. The first is a custom-built microfluidic chip — a small, flat platform similar in size to a computer chip — with multiple inlets that each ‘prints’ a different material. The other component is a digital micromirror, an array of more than a million tiny mirrors that each moves independently.”

“The researchers used different types of hydrogels – materials that, after passing through the printer, form scaffolds for tissue to grow into. The micromirrors direct light onto the printing surface, and the illuminated areas indicate the outline of the 3D object that’s being printed. The light also triggers molecular bonds to form in the materials, which causes the gels to firm into solid material. As the 3D object is printed, the mirror array changes the light pattern to indicate the shape of each new layer.”

“The process is the first to use multiple materials for automated stereolithographic bioprinting — an advance over conventional stereolithographic bioprinting, which only uses one type of material. While the demonstration device used four types of bio-inks, the study’s authors write that the process could accommodate as many inks as needed.”

The team “also printed shapes mimicking tumors with networks of blood vessels, which could be used as biological models to study cancers. They tested the printed structures by implanting them in rats. The structures were not rejected.”